8 Years of Vibration leading to engine knock?

[UpgradeXP]

I appreciate any help I can get. 8 years go a family member replaced the 3.9L motor in my 2004 Mustang. Ever since then there has been a vibration at idle when in drive and foot on the brake. It feels rhythmic where the vibration frequency ramps up to a point then slowly goes back down and repeats. I replaced the IAC, MAF, spark plugs, ignition coil and wires, smoke tested for vacuum leaks, replaced fuel pump and filter. Then the balancer bolt broke and after replacing that I got tired of nothing working so I ignored it for 6 years and 30,000 miles.

In 2024 I started working on it again and I've replaced the exhaust manifolds, transmission mount, engine mounts, cam synchronizer, and harmonic balancer. Still not fixed and worse I start to hear a high pitch ringing sound like a bike bell.
Sorry about the power steering pump. Earlier pinging sound


I assumed it was the timing chain so I replaced the chain, gears and guide and heard the same sound but much less frequently and after a week it went away and I now hear this sound.
Knocking sound now WITHOUT belt with microphone next to balancer


And I still have the vibration! I did notice the exhaust leak is back. Is this rod knock? Or did my aftermarket cam synchronizer go bad? I'm hoping for some direction.

Thank you.

Edited sound links to soundcloud instead.

 

[Noobz347]

 

[UpgradeXP]

Thank you, thought Google drive would be a good way to link the audio. I changed it to SoundCloud instead.

 

[Noobz347]

Well... There's not much I can tell you from those sound recordings.

Maybe it's time to bite the bullet and do a rebuild.

Have you pulled codes and performed a cylinder balance test? How about a compression test?